Breast-feeding for longer 'cuts risk of cancer'

Women can "significantly" reduce the risks of breast cancer by breast-feeding babies for longer, the biggest study of its kind has shown.

The protective effects are so strong that 1,000 cases of cancer could be avoided in Britain each year if every baby was breast-fed for an additional six months.

The study of more than 150,000 women from 30 countries also found that having more children reduced the risk of breast cancer.

British scientists behind the study believe breast cancer rates are lower in the developing world because women have more children and tend to breast-feed infants until they are two years old.

Prof Valerie Beral, of the Cancer Research UK epidemiology unit at Oxford University and author of the study, said: "These results are a major step forward in our understanding of why breast cancer incidence is so high in developed countries. It's long been known that breast cancer is common in situations where women have few children and breast-feed for short periods."

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She said the link had not been so conclusively shown before because previous studies had been too small.

The link between breast cancer and not having babies has been suspected for hundreds of years. In 18th century Italy, the researcher Bernardino Ramizzina described breast cancer as an "occupational disease of nuns".

The new study, in The Lancet, found that each child reduced the risk of developing breast cancer by the age of 70 by seven per cent.

For every year a woman breast-fed, the risk fell by an additional 4.3 per cent. The protective effects were just as strong in women with a family history of breast cancer.

The findings suggest that the number of breast cancers in British women would be halved if they had half a dozen children and breast-fed them until they were two or three.

Dr Gillian Reeves, a co-author of the paper, said: "If women in the West were to breast-feed each of their children for an extra six months, this could prevent five per cent of breast cancers each year."

In Britain, 30 per cent of mothers do not, or cannot, breast-feed. By the time babies are six weeks old, only 42 per cent of all infants are being breast-fed, while only one in five mothers are breast-feeding after six months.

The researchers said the reason why breast-feeding cut the risk of cancer was unclear.

Belinda Phipps, chief executive of the National Childbirth Trust, said: "We need to see a real shift away from the current bottle-feeding culture in the UK to one where breast-feeding is completely accepted and supported by society.

"Breast-feeding should become as unremarkable as reading a newspaper, so that more women are able to follow their instincts and breast-feed wherever and whenever their baby needs to be fed."

A total of 39,000 breast cancer cases are diagnosed in Britain each year and 13,000 women die from the disease.